…如果只有一个匹配的可能条目(主键的WHERE子句)？
SELECT `x`
FROM `unicorns`
WHERE `id` = 123
LIMIT 1
…相同,但现在它是DELETE：
DELETE FROM `unicorns`
WHERE `id` = 123
LIMIT 1
……和更新：
UPDATE `unicorns`
SET `rainbows` = `rainbows` + 1
WHERE `id` = 123
LIMIT 1
附：列ID是主键,因此它是唯一的.
谢谢你的建议！
最佳答案
这取决于您是否有列索引
DELETE FROM `unicorns` WHERE `id` = 123 LIMIT 1
如果id是主键,则没有意义,但是
DELETE FROM `unicorns` WHERE `noindexoclumn` = 123 LIMIT 1
会给你提高性能